An Overview of Classical and Emergent Materials for Spin-Orbit Torque Applications
Chi-Feng Pai1*
1Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan
* presenting author:Chi-Feng Pai, email:pai.chifeng@gmail.com
Magnetoresistive random access memory (MRAM) has come a long way: It took more than a decade to evolve from the first generation “toggle-mode” MRAM to the now-standard second generation “spin transfer torque” MRAM (STT-MRAM). The discovery of spin transfer torque mechanism for magnetization switching is not only a purely scientific discovery but also a major breakthrough in terms of MRAM architecture engineering: It made the device scalable down to 10nm scale. More surprisingly, researchers found that even by using certain heavy transition metals, such as Pt, Ta, and W, new types of “spin-orbit torque” (SOT) can also be generated by the spin-orbit interaction in these normal metals. This led us to alternative designs of potential SOT-MRAMs. In this talk, I will review some of these not-so-recent discoveries of the SOT from classical materials (2012-2014), and discuss the possibility of building more energy efficient MRAM devices out of certain emergent materials (2014-now).


Keywords: spintronics, spin Hall effect, spin transfer torque, spin orbit torque, emergent materials